.month {
  height: 140px;

  &-background-img {
    background-image: url(https://yjy-teach-oss.oss-cn-beijing.aliyuncs.com/reactbase/ka/month-bg.png);
    background-repeat: no-repeat;
    background-size: contain;
    width: 100%;
  }
}

.arrow {
  display: inline-block;
  width: 7px;
  height: 7px;
  margin-top: -3px;
  margin-left: 9px;
  border-top: 2px solid #121826;
  border-left: 2px solid #121826;
  transform: rotate(225deg);
  transform-origin: center;
  transition: all 0.3s;
}

.expand {
  transform: translate(0, 2px) rotate(45deg);
}